1. Field of the Invention
The present invention relates to an image forming apparatus in which a stored electronic file is erased when a retention period expires or a designated time is reached.
2. Description of the Background Art
Electronic paper is a thin display technology similar to a liquid crystal display and the like, and it has similar appearance as ordinary paper. The electronic paper is characterized in that displayed contents are electrically rewritable, and that power consumption thereof is very low as electric power is unnecessary to retain the displayed contents. In addition, electronic paper is non-volatile, that is, once the displayed contents are rewritten, the displayed contents are maintained even when power is turned off. Attempts to apply electronic paper as such have been made in various technical fields.
Japanese Patent Laying-Open No. 2003-209718 (Document 1) proposes a technique of utilizing electronic paper in a digital camera. According to the technique disclosed in Document 1, when a power button is pressed by a user while the power is on, remaining battery level is calculated, and the maximum number of pictures that can be taken is calculated from available memory space. These pieces of calculated information are output to electronic paper, and on the electronic paper, information related to the remaining battery level and the maximum number of pictures that can be taken at present is displayed. Even when the power of digital camera is turned off thereafter, the displayed contents of information related to the remaining battery level and the maximum number of pictures that can be taken before power-off are maintained.
Further, Japanese Patent Laying-Open No. 2006-201460 (Document 2) proposes a technique of utilizing electronic paper in an image forming apparatus such as a multifunctional printer. According to the technique disclosed in Document 2, information related to image formation, such as counter information and information of supplies, is displayed on electronic paper. This allows collection of necessary pieces of information without turning on the power.